418 APPLICATION OF METHODS OF BACTERIOLOGY 



crisis they may be found in the sputum of the patient alive, 

 fully virulent and in almost countless numbers. It has been 

 suggested that after about a week there develops in the 

 tissues of the body a sufficient amount of antibodies to 

 neutralize the .poison of the pneumococci and that coincident 

 with this neutralization there is a cessation of the evil 

 effects, i. e., the crisis occurs. Vague as this may appear 

 it is probably as satisfactory as any other explanation 

 available at this time. There are objections or criticisms 

 that may, however, be offered in discussing it. If that be 

 the correct explanation of the crisis, one might reasonably 

 expect to detect in the blood of convalescents from pneumonia 

 protective antibodies in sufficient amount and with such 

 constancy as to support the view, but such is not always 

 the case. In some instances antibodies are found in the 

 blood immediately after the crisis in such amounts that a 

 fraction of 1 cubic centimeter of the serum will protect 

 a mouse from infection by a hundred fold the ordinary 

 fatal dose of virulent homologous pneumococci; in other 

 cases no such protective bodies are to be demonstrated at 

 all; in the majority of cases limited amounts of such pro- 

 tective agents are to be demonstrated. In some cases pro- 

 tective bodies may be detected in the blood a few hours 

 after the crisis, and none may be found a few days later. 

 It is such inconstancies as these that call into question 

 the explanation offered above, or at least justify the sus- 

 picion that the crisis may be dependent upon other forces 

 in addition to those having to do with the neutralization of 

 poison or the destruction of a certain number of the germs. 

 It has been suggested that such other factors may com- 

 prise provisions for preventing further growth of the pneu- 

 mococci in the tissues without actually killing them or 



